采用3码片的超结构光纤布拉格光栅(SSFBG)作为编/解码器，该编/解码器光栅包含3段子光栅(空间码片)，在相邻的空间码片的边界处存在离散的四相相移(0,π/2,π,3π/2)。利用四相编解码所具有的良好自相关和互相关特性，成功实现了单信道速率高达40 Gb/s，码片速率高达240 Gchip/s的全光编解码实验。据我们所知，这是利用光纤布拉格光栅作为编/解码器的全光码分复用(OCDM)系统所达到的最高单信道传输速率。理论计算和实验结果表明了利用超结构光纤布拉格光栅(SSFBG)实现多相高速全光编解码的可行性。这样高速的全光编解码可以应用于光码分复用系统和分组交换网络。

Encoders and decoders using 3-chip superstructured fiber Bragg gratings(SSFBGs) are designed, in which every encoder/decoder grating consists of three subgratings. The grating has an uniform amplitude refractive index level along its length, in which discrete (0,π/2,π,3π/2) jumps in phase are written into the grating at the boundaries of adjacent spatial chips. Quaternary encoding and uncoding can provide codes with desirable auto and cross-correlation characteristics with which the three-chip, 240-Gchip/s all optical encoding and decoding is achieved. As much as we know, this is the highest single channel rate obtained from fiber Bragg grating (FBG) based OCDM system. The agreement between experimental and calculated results indicates the feasibility of multi-phase all optical encoding and decoding using SSFBG. And such all optical encoding and decoding is required in optical code division multiplexing (OCDM) systems and packet-switched networks.